On Thursday, December 13, 2018, Longwen CHEN, a PhD student in energetics and process engineering at the Laboratory for Optimization of Environmental Design and Engineering (LOCIE), will submit his thesis "Étude Expérimentale de la Décharge Couronne pour le Traitement de l'Air Intérieur : COV et Particules".
The defense will take place at 10:30 am, Amphi 30, in building 3 (Pôle Montagne) on the Bourget-du-Lac campus.
Summary of the thesis
Indoor air quality has become a public health concern, particularly in view of the increasing amount of time spent in indoor environments and enclosed spaces. The aim of this work is to develop processes using corona discharge to treat chemical and particulate gaseous pollutants in indoor air. The first part of the work concerns the degradation of chemical gaseous pollutants present in very low concentrations in indoor air. The coupling of a corona discharge and a catalyst is used to degrade toluene under conditions representative of indoor air. This study demonstrates the excellent efficiency of corona discharge on toluene at low energy densities. It identifies the optimum operating conditions and proposes reaction mechanisms following identification of the main reaction products. However, plasma generates undesirable species such as ozone and nitrogen oxides, which must be destroyed. We chose to add a transition metal oxide catalyst (MnOx/Al2O3) to the corona discharge. Different catalysts are synthesized and then modified by grafting modifying agents. Their effectiveness against ozone and NOx is quantified in the presence of different levels of water vapour. The second part concerns the collection of particles by electrostatic filtration. Three processes are studied, combining an ionization stage and a collection stage. Ionization is provided either by a wire-plate electrofilter or by needles raised to a potential of a few kilovolts. Collection efficiency is measured in the 10 nm to 20 µm range, as a function of various operating parameters (voltage, polarity, speed, geometric parameters, particle concentration, humidity, etc.). Needles are slightly less efficient than electrostatic precipitators, but produce very little ozone and consume less energy. The parametric study enables us to dimension and optimize the process geometry and define the best operating conditions.